Development of a SWMM-GIS Flood Model for New Orleans Drainage Pumping Station No 4 Basin

Author

Giron, Efrain

Document Type

Dissertation;

Keywords

Stormwater

Abstract

An urban flood damage model for the drainage area serve by
Pump Station No. 4 (Prentiss, New Orleans, Louisiana) has been
completed. This study presents the research effort needed to
develop a stormwater management model (SWMM) integrated
with GIS that includes a Damage Model to estimate the losses
produced by storm events on flood prone areas. The latest LIDAR
data are used for the topography. The drainage area for this study
covers approximately 3218 acres, with elevations ranging from -9
ft to 6 ft above sea level. The runoff produced is pumped into
Lake Pontchartrain via London Outfall Canal. The study area
includes a pump station with a capacity of 106 m3/s and a
complex drainage system including a 10 ft siphon that drains the
runoff on the western side. The hydrology and hydraulic routing
for the watershed was estimated using the U.S. EPA Storm Water
Management Model (SWMM) and the input of the model was
created using a geodatabase composed of nodes, conduits and
subcatchment areas developed in ArcGIS 8.2. The GIS was
designed to take advantage of the importing node and graphic
capabilities of the SWMM. Since all features used by SWMM
were georeferenced, node flood elevation data were transferred
back for display in geographic space. This approach allows for a
more accurate volume computation of flooded areas by using
Boolean operations on a Triangular Irregular Network (TIN)
surface of node elevations and a TIN surface of LIDAR elevation
data. Flood volumes were obtained for the study area by
simulating a series of rain events. These flood volumes were then
incorporated into a Damage model to estimate damage rating
curves for the study area. The 1:100 year damage was estimated
to be 17.2 million of dollars (2005 US dollars). The average
annual flood damage was estimated to be 5.5 million of dollars
(2005 US dollars). The developed Annual Flood Maps can be
used to set rational flood insurance rates or to plan improvements
to the drainage system. This information can be used by FEMA
and by the private insurance industry of the State

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